Introduction
The male reproductive system mostly exists outside of your body. The external organs include the penis, scrotum and testicles. Internal organs include the vas deferens, prostate and urethra. The male reproductive system is responsible for sexual function and urination.
The male reproductive system includes a group of organs that make up the reproductive system and urinary system in men and people Assigned Male at Birth (AMAB).
The male reproductive system contains internal and external parts. Internal parts are inside your body, and external parts are outside your body. Together, these organs help you urinate (pee), have sexual intercourse and make biological children.
Anatomy
External Parts
Most of the male reproductive system is on the outside of your abdominal cavity or pelvis. The external body parts of the male reproductive system include the penis, scrotum and testicles. Another name for these parts is genitals or genitalia.
Penis
The penis is the male organ for sexual intercourse. It contains many sensitive nerve endings, and it has three parts:
Root. The root is the base of your penis. It attaches to the wall of your abdomen.
Body (shaft). The body has a shape like a tube or cylinder. It consists of three internal chambers: the two larger chambers are the corpora cavernosa, and the third chamber is the corpus spongiosum. The corpora cavernosa run side by side, while the corpus spongiosum surrounds your urethra. There’s a special, sponge-like erectile tissue inside these chambers. The erectile tissue contains thousands of spaces. During sexual arousal, the spaces fill with blood, and your penis becomes hard and rigid (erection). An erection allows you to have penetrative sex. The skin of the penis is loose and stretchy, which lets it change size when you have an erection.
Glans (head). The glans is the cone-shaped tip of the penis. A loose layer of skin (foreskin) covers the glans. Healthcare providers sometimes surgically remove the foreskin (circumcision).
In most people, the opening of the urethra is at the tip of the glans. The urethra transports pee and semen out of your body. Semen contains sperm. You expel (ejaculate) semen through the end of your penis when you reach sexual climax (orgasm).
When your penis is erect, your corpora cavernosa press against the part of your urethra where pee flows. This blocks your pee flow so that only semen ejaculates when you orgasm.
Normal size of the penis
Studies suggest that the average penis is about 3.5 inches (8.9 cm) when flaccid (soft) and a little more than 5 inches (13 cm) when erect.
Scrotum
The scrotum is the loose, pouch-like sac of skin that hangs behind the penis. It holds the testicles (testes) as well as nerves and blood vessels.
The scrotum protects your testicles and provides a sort of “climate-control system.” For normal sperm development, the testes must be at a temperature that’s slightly cooler than body temperature (between 97 and 99 degrees Fahrenheit or 36 and 37 degrees Celsius). Special muscles in the wall of the scrotum let it contract (tighten) and relax. Your scrotum contracts to move your testicles closer to your body for warmth and protection. It relaxes away from your body to cool them.
Testicles
The testicles (testes) are oval-shaped organs that lie in your scrotum. They’re about the size of two large olives. The spermatic cord holds the testicles in place and supplies them with blood. Most people AMAB have two testicles, on the left and right side of the scrotum. The testicles make testosterone and produce sperm. Within the testicles are coiled masses of tubes. These are the seminiferous tubules. The seminiferous tubules produce sperm cells through spermatogenesis.
Epididymis
The epididymis is a long, coiled tube that rests on the back of each testicle. It carries and stores the sperm cells that your testicles create. The epididymis also brings the sperm to maturity — the sperm that emerge from the testicles are immature and incapable of fertilization. During sexual arousal, muscle contractions force the sperm into the vas deferens.
Internal parts
There are several internal (accessory) organs in the male reproductive system. They include:
Vas deferens
The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, just behind the urinary bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.
Ejaculatory ducts
Each testicle has a vas deferens that joins with seminal vesicle ducts to form ejaculatory ducts. The ejaculatory ducts move through your prostate, where they collect fluid to add to semen. They empty into your urethra.
Urethra
The urethra is the tube that carries pee from your bladder outside of your body. If you have a penis, it also ejaculates semen when you reach orgasm.
Seminal vesicles
The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. Seminal vesicles make up to 80% of your ejaculatory fluid, including fructose. Fructose is an energy source for sperm and helps them move (motility).
Prostate gland
The prostate is a walnut-sized gland that rests below your bladder, in front of your rectum. The prostate adds additional fluid to ejaculate, which helps nourish sperm. The urethra runs through the center of the prostate gland.
Bulbourethral (Cowper) glands
The bulbourethral glands are pea-sized structures on the sides of your urethra, just below your prostate. They create a clear, slippery fluid that empties directly into the urethra. This fluid lubricates the urethra and neutralizes any acids that may remain from your pee.
Function
The organs that make up the male reproductive system perform the following:
Produce, maintain and transport sperm cells and semen. Sperm cells are male reproductive cells. Semen is the protective fluid around sperm.
Discharge sperm.
Produce and secrete male sex hormones.
The entire male reproductive system depends on hormones. Hormones are chemicals that stimulate or regulate activity in your cells or organs. The primary hormones that help the male reproductive system function include:
Follicle-stimulating hormone (FSH). Your pituitary gland makes FSH. FSH is necessary to produce sperm (spermatogenesis).
Luteinizing hormone (LH). Your pituitary gland also makes LH. LH is necessary to continue the process of spermatogenesis.
Testosterone. Testosterone is the main sex hormone in people AMAB. It helps you develop certain characteristics, including muscle mass and strength, fat distribution, bone mass and sex drive (libido).
Conditions and Disorders
Common conditions that affect the male reproductive system include:
Testicular cancer.
Penile cancer.
Prostate cancer.
Sexually transmitted infections (STIs).
Premature ejaculation.
Male infertility.
Erectile dysfunction.
Priapism.
Common signs of conditions that affect the male reproductive system include:
Lumps or sores on your external reproductive parts.
Pain or swelling.
Aching or discomfort around your groin or lower abdomen.
Blood in your semen (hematospermia).
Blood in your pee (hematuria).
Pain or burning when you pee (dysuria).
Loss of bladder control (urinary incontinence).
Inability to get and maintain an erection hard enough for sexual intercourse.
Care
Practice safe sex. Use condoms to help protect yourself against STIs.
Perform self-examinations. Regularly examine your penis, scrotum and testicles for any changes.
Get the human papilloma virus (HPV) vaccine. This vaccine helps protect you from HPV, which can cause penile cancer and genital warts.
Consider circumcision. A circumcision reduces your risk of penile cancer.
Don’t use tobacco products. Tobacco products increase your risk of developing cancers. If you smoke, ask a healthcare provider for tips to help quit smoking.
Practice good hygiene. It’s a good idea to regularly clean your penis, scrotum and the surrounding areas with soap and warm water to help kill germs that cause infections. If you still have your foreskin, be sure to pull back your foreskin, clean the head of your penis and thoroughly dry the area.
Get regular prostate exams. Prostate exams look for early signs of prostate cancer. You should get your first prostate exam by age 50. However, if you have a biological family history of prostate cancer, it’s a good idea to get your first prostate exam by 45.
Maintain a weight that’s healthy for you. Ask your provider what a healthy weight means for you.
Educate yourself about STIs. Learn about the signs and symptoms of STIs. The more you know, the better you can protect yourself and your partner(s).
